Local battery-circuit for multiple-switch-board systems



(No Model.) 2 Sheets-Shet'I.

J. A. SEELY.

LOGALB-ATTERY CIRCUIT FOR MULTIPLE SWITCH BOARD SYSTEMS. No. 357,540.Patented Feb. 8, 1887 III o in. I I

|;IK I1 i! I h: F" I i I I I I I (No Modl.) I 2 Sheets-=Sheet 2..

J. A. CEELY. LOCAL BATTERY CIRCUIT FOR MULTIPLE SWITCH BOARD SYSTEMS.N0.'357,540.- .Pafnented Feb. 8, 1887..

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UNITED STATES PATENT Fries.

JOHN A. SEELY, OF NEW YORK, N. Y., ASSIGNOR 'IO THE WESTERN ELEG- TRIOCOMPANY, OF CHICAGO, ILLINOIS.

ILOCAL'BATTYERY-CIRCUIT FOR MULTlPtE-SWlTCH-BOARD SYSTEMS.

SPECIFICATION forming part of Letters Patent No. 357,540, dated February8, 1887.

Application filed November 15, 1886. Serial No. 218,950. (No model.)

To aZZ whom it may concern.-

Be it known that 1, JOHN A. SEELY, acitizen of the United States,residing at New York, in the county of New York and State of New York,have invented a certain new and useful Improvement in LocalBattery-Circuits for lifultiple-Switch-Board Systems, (Case 5.) of whichthe following is a full, clear, concise, and exact description,reference being had to the accompanying drawings, forming a part of thisspecification.

My invention relates to multipleswitchboard systems of atelephoneexchange in which metallic circuits are'employed.

The object of my invention is to provide circuits whereby the localbatteries at the different subscribers stations may be utilized astest-batteries when the subscribers telephones are not in use.

My invention will be readily understood by reference to the accompanyingdrawings, in which-- Figurel is a drawing showing two metallic circuitsconnected with their switches, respectively, on two multipleswitch-boards and the operators telephone and switching apparatus at thedifferent boards. Fig. 2 is a diagram illustrative of the circuits of aline at a subsoribersstation. Fig. 3 is a sectional view of one of theloop-plugs and the connections of the two strands of the flexible cordwith the point and insulated sleeve upoh the shank thereof.

In the different figures like parts are indicated by the same letters ofreference.

The connections at the central office and the apparatus may be the sameas heretofore used, except that the test-battery is omitted from thecircuits of the telephones at the different boards. Thus the circuit ofline a may be traced through the spring-jack of each of the boards andthrough an annunciator to ground. The branch b,or other side of themetallic circuit, is connected with the insulated frame of said switchesand is normally open. The loopplugs and double-stranded cords areprovided for connecting the differentlines together.

Referring to Fig. 2, it will be seen that branch a is shown connectedwith the bell and generator to contact'point c of the subscribersswitch. The switch-lever,when the telephone is in place, is closedagainst said contactpoint through the local battery 6.

c and against ground-contact point d. The subscribers bell and generatorare thus included in the circuit of the branch a when the telephone ishung up.

Branch 1) of the telephoneline is shown permanently connected with theswitch -lever mally open at the central office, the battery 6 will notrun down. Line or wire b may thus be traced normally from the insulatedframes of its switches upon the switchboards to the subscribersstation,and thence through a battery, e, and the switch-lever to groundthrough contact d, as shown.

Wire a may be traced from ground at the central office through anindividual annunciator,a springjack switch on each of the switchboards,and thence to the subscribers station, thence through the bell andgenerator to the switch-lever, and thence to ground. T

The subscriber, by means of his generator, throws down the individualannunciator at the central office in the usual manner to notify theoperator of the call. The operator thereupon makes the necessaryconnection with a springjack of the line by inserting a plug in thespring-jack, as shown at the first board, Fig. 1. As the subscriberremoves his telephone from the switch-lever the switch is separated fromground-contact d and the contact-point c of the'branch of the wire acontaining the bell and generator, and closes upon contact-point f ofthe local circuit and contact-point g of the branch of the line acontaining the telephone and induction coil. Battery eis thusshortcircuited by the local or transmitter circuit, and the wiresab areunited together at the subscribers station in metallic circuit. Thismetallic circuit may be traced by line a through the telephone to point9, and thence through the battery 6 to wire I). The battery e beingshort-circuited, as before described, will not send any appreciablecurrent over the subscribers metallic circuit a b. The battery 6 is thusused as a local battery when the telephone is removed from the switch,and when the telephone is upon the switch this battery is included inthe open branch wire I).

Referring now to Fig. 1, it will be seen that wire b is permanentlyconnected with the insulated frames of the switches of the line on the-different boards. By closing a ground- As wire b is nor- IOO circuit atany switch-board to the frame or test-piece of the switch of any line itmay be determined whether or not the subscribers telephone is hung uponthe switch-lever. If hung upon the switch-lever, the local battery 6will be included in the branch I) of the line which is being tested, andcurrent will thus be sent through the operators telephone. If, however,the telephone is removed from the subscribers switch, the operator willget no current when he tests at one of the insulated plates or frames ofthe switch of the line. Thus if he hears a click in his telephone whenhe makes the test he will know that the line is free, and if he hears noclick he will infer that the line is busy.

Having thus described myinvention, I claim as new and desire to secureby Letters Patent- 1. In a metallic circuit multiple-switchboard system,a telephone-line one branch of which is connected through a switch oneach of the switch boards and annunciator to ground, and at thesubscribeflsstation through a bell and generator to the telephone-switchand to ground, the other branch of said line being connected with theinsulated frames of said switches and thence to the subscribers stationand through a battery to the telephone switch and to ground, incombination with switching apparatus at the subscribers station, wherebysaid battery may be included in a local circuit and said branches to andI) united in metallic circuit, substantially as shown and described.

2. In a telephone-exchange system, a wire, I), connected with aninsulated frame or testpiece on each of two or more switch-boards andextending to a subscribers station through a battery, e, and thetelephone switch to ground, in combination with a telephone included ina normally-open ground-circuit at the subscribers station, whereby onclosing said circuit current will be sent from the battery through saidtelephone to indicate the position of the switch-lever at thesubscribers station.

3. In a telephone-exchange system, a metallic circuit consisting of twobranches, one of said branches, a, being normally connected from groundat the central office through an annunciator and switch on each of twoor more multiple switch-boards, said branch extending to the subscribersstation and being connected at the subscribers station with a bell andgenerator and a telephone, the other branch, b, of said line beingconnected normally at the central office with the insulated test platesor frames of said switches and extending to the subscribers station, andthrough a battery, 0, to the telephone-switch lever, in combination witha ground-connection from said subscribers switch-lever and the localcircuit of the transmitter and switching apparatus, substantially asdescribed.

In witness whereof I hereunto subscribe my name this 6th day ofNovember, A. D. 1886.

JOHN A. SEELY.

Vitnesses:

H. B. THAYER, A. L. SALT.

